A gear motor assembly for a sunroof usually includes a casing having a through hole, a motor fixed to the casing, a gear housed in the casing, and a bearing fixed in the hole. The gear has a shaft running through the hole and sleeved by the bearing. The shaft couples to the sunroof During operation, the shaft rotates with respect to the bearing. In most gear motor assemblies, the inner wall of the bearing and the outer wall of the shaft are smooth arcuate surfaces. In order to reduce vibration or wobbling of the gear during rotation, the gap between the shaft and the bearing is designed as small as possible which leaves little room for receiving lubricant. Thus, less lubricant can be accommodated in the gap, resulting at times in hard contact between the shaft and the gear during rotation and, therefore, produces a loud noise.
Hence there is a desire for a new gear motor assembly producing less noise during operation.